Gas turbines include individual burners that may interfere with each other during operation. This can prevent an efficient operation of the turbine and lead to increased emission, in particular to the increase of nitrogen oxides (NOX), an uneven flame temperature, oscillations and so forth. These unwanted effects may occur under atmospheric conditions as well as under pressurized combustion processes. Gas turbines often include orifices that are used to equalize the fluid flow to the individual burners of the gas turbine in order to compensate for these effects.
The burners in the gas turbine receive fluid from a manifold which usually includes an inlet and several outlets. This may lead to pressure difference over a length of the manifold and also at the position of the burners. Additionally, differences may occur due to tolerances introduced while manufacturing manifolds and burners to the gas turbine.
The differences are equalized by altering the size of openings in the orifices; this adjustment or modification needs to be performed regularly and is a time consuming and expensive process.
Use of piezoelectric valves in place of the orifices obviates the above mentioned problem since piezoelectric valves can adjust or control the mass flow due to the presence of piezoelectric actuator. In this type of arrangement the piezoelectric valve including the actuator are arranged axially in the fluid flow path.
However, piezoelectric actuator may be damaged while coming in contact with hot fluid which has a temperature greater than about 140 degrees centigrade. Additionally, it may also be difficult to place the piezoelectric actuator on the gas turbine since auxiliary systems and other components such as pipes often limit the available space.
U.S. Pat. No. 6,062,532A teaches an electric solid-body actuator having a hydraulic displacement (amplitude) magnifier which has a leakage-free construction and, at the same time, permits a temperature compensation, as a result of which, for example, an extended operation of a setting member into defined switching positions may be achieved.
U.S. Pat. No. 5,857,662A teaches an electrically activatable stop device which possesses good dynamic properties. Moreover, the stop device is to have a compact design, work in an operationally reliable manner and be capable of being used within a wide temperature range.